A pulse wave torpedo detonates within a subspace rupture.

A pulse wave torpedo was a type of starship-mounted projectile weapon which was used by the 22nd century.

In the mid-23rd century, a Vulcan science mission detonated a pulse wave torpedo inside a subspace rupture which they had encountered in the Hanoli system, in an attempt to seal the tear. Their plan backfired, however, and the entire Hanoli system, including the Vulcans, was destroyed.

In 2369, upon encountering what they thought was another subspace rupture, the crew of Deep Space 9 attempted to improve upon the intentions of the Vulcans by detonating a pulse wave torpedo inside the rupture. It was hoped that their effort would be more successful, as better ways of controlling the flux density had been developed in the intervening years. The effort proved futile, however, and the rupture continued to expand. (DS9: "If Wishes Were Horses")

Despite the event being explicitly said to have happened in the mid-23rd century, when talking about the device the Vulcans used O'Brien said the technology had much improved in the last two hundred years, implying Pulse Wave Torpedos were around at least since the 22nd century.
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